Spray-on insulation

ABSTRACT

The present invention, in certain embodiments discloses an insulation composition including polyvinyl alcohol cooked without an acidic medium and cellulose fibers combined with an acidic medium for spray-on insulation. In certain embodiments cellulose fibers and acidic solids are ground together. In one aspect the acidic medium is solid boric acid. In another aspect liquid boric acid is sprayed onto the fibers Systems are disclosed for introducing the fiber acidic composition into a first hose of a spray nozzle while introducing polyvinyl alcohol into a second hose of the spray nozzle. In another aspect an acrylic resin is mixed with the polyvinyl alcohol.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention is directed to fibrous cellulose spray-on insulation, adhesives used therewith, and to methods for their use.

2. Description of Related Art

The prior art discloses a wide variety of spray-on cellulose insulation materials and systems. Certain prior art compositions used in spray-on insulation systems include an adhesive which is a mixture of sodium silicate and an acrylic resin. A homogeneous mixture of these two ingredients is achieved by combining them with a high speed shearing-mixing action. After a period of time the ingredients of the mixture can settle out and separate from each other. Under prolonged storage conditions such a mixture will gel and then require laborious re-mixing, e.g. with a high speed mixer. Other disadvantages of such adhesives include: limited flexibility; limited freeze/thaw (temperature differential) stability; and limited water resistance; and the requirement for additional handling, mixing, etc. at a job site. Such prior art compositions are also typically used in a ratio of water to adhesive 3:5; and at a ratio of such a mixture (water+adhesive) to fiber of 0.23 gallons of mixture to about one pound of fiber. It would be desirable in certain embodiments to be able to use less adhesive concentrate to reduce transport cost and material expense.

Polyvinyl alcohol ("PVOH") is a known adhesive which, for many applications is dissolved in water prior to use and "cooked". Typically this cooking involves dispersing particles of PVOH in water at ambient temperature and raising the resulting mixture's temperature to between 180 and 205 degrees Fahrenheit (85 to 96 degrees C.) for about 30 minutes. It is known in certain PVOH cooking processes to add an acidic medium (e.g. boric acid) to PVOH during the cooking process to improve the resulting material's wet strength, water resistance and fire retardancy. To prevent gelling, the pH of a homogeneous amount of PVOH and boric acid is adjusted, from the range of 6.7-7.3 to between about 4.5 to 4.7, e.g. by adding an acid (such as citric acid or phosphoric acid). The pH is monitored and maintained between 4.5 to 4.7 as boric acid is added. Addition of acid to the PVOH can result in a more corrosive material which must be safely contained, packaged, transported and used. Also, the amount of acid that can be added is limited by the saturation level of water at ambient temperature.

SUMMARY OF THE PRESENT INVENTION

The present invention discloses a spray-on insulation material with improved water resistance, fire retardancy, and wet strength.

The present invention, in certain embodiments, discloses a two component spray-on insulation. One component is polyvinyl alcohol ("PVOH") cooked without the addition of an acidic medium; or such PVOH with an additive such as an acrylic polymer. Another component is a combination composition which includes cellulose fibers (e.g. as described in U.S. Pat. Nos. 4,360,440; 5,082,563; 5,195,465; and 5,352,780) and a cross-linking substance, e.g. an acidic medium (solids and/or liquid); e.g. (but not limited to) granular boric acid solids (e.g. about the size of table salt granules) for supplying a borate ion such as those commercially available from U.S. Borax Co. These solids are powderized to reduce them in size (e.g. to about the size of particles of commercially available baby powder). Milling typically occurs at a temperature of about 165° F. with an air flow through the mill. Air flow is used to convey fibers in various processing steps resulting in a moisture content in the fibers of about 10 to 15 percent by weight. In other embodiments liquid borax is used.

In certain embodiments the cellulose fibers and acidic solids are mixed together; in other embodiments they are ground together in a processing mill (e.g. a hammer mill available from Williams Co., Grundler Co., Jacobs Co., or Bliss Co.). In one embodiment about 75 to 85 pounds of fibers (2.5 mm in an average largest dimension) are mixed or milled with about 15 to 25 pounds of powdered boric acid solids. In another embodiment the treated fibers have ingredients ranging, by weight, as follows (the total percentage of finished product having components within the stated ranges equalling one hundred percent):

between 75% to 85% cellulose fibers

between 10% to 25% solid boric acid

between 0% to 12% (in certain embodiments 8% to 12%) sprayed-on aqueous boric acid

(Examples: 75% cellulose fibers and 25% solid boric acid; 75% cellulose fibers, 17% solid boric acid, 8% aqueous boric acid; 81% cellulose fibers, 10% solid boric acid, 9% aqueous boric acid)

In one aspect fibers mixed together with the acidic medium and/or milled with the acidic medium are also sprayed with an aqueous liquid acid solution to further coat and/or impregnate them with the acidic medium. In one embodiment the fibers are sprayed with the acidic medium with a one-nozzle device or with a two-nozzle device as shown, e.g., in FIG. 7 of U.S. Pat. No. 5,429,741 (incorporated in its entirety herein by reference).

In another embodiment cellulose fibers are fed through a first hose to an insulation composition spray nozzle and the acidic medium is fed through a separate second hose to the nozzle so that the acidic medium is applied to the cellulose fibers within and as they leave the nozzle. Adhesive composition is introduced through another hose to the nozzle.

In one spray-on insulation system according to the present invention the cellulose-fiber-acidic-solids mixture as described above is introduced through one hose to an insulation spray nozzle (e.g. as shown in U.S. Pat. No. 4,187,983) and a liquid PVOH adhesive is introduced into the spray nozzle through another hose. In other embodiments the liquid PVOH adhesive is mixed with a liquid acrylic polymer, or, acrylic resin or emulsion, such as (but not limited to) FT-9™ PVC material, B. F. Goodrich Co.; 1415™ vinyl acrylic material, Rhone-Poulenc Co.; 6326™ vinyl acrylic material, Rohm & Haas Co.; 1845™ vinyl acrylic material, B. F. Goodrich Co.; 1199™ Styrene acrylic latex, Rhone-Poulenc Co.; 526 BP™ vinyl acetate, Air Products Co.; and Res. 7800™ polyvinyl acetate copolymer, Unocal Co.; and the mixture is fed to the spray nozzle. The added acrylic polymer increases the resulting product's toughness, water resistance fire retardancy, elasticity and bonding ability.

In other embodiments of another aspect of the present invention, treated fiber (as described above and below, treated with ground-in acidic solids and/or with sprayed on liquid acid) is used in a spray-on insulation with prior art PVOH that is cooked with an acidic medium, and with such PVOH that is cooked with the addition of additional acid as described above. Such adhesives are usable in embodiments similar to those described herein in place of the adhesives according to this invention and in the same proportions.

In certain embodiments of the present invention fibers and methods of their use are provided which make available more boric acid for the final product than prior art materials and methods in which boric acid is added to cooking PVOH.

It is, therefore, an object of at least certain preferred embodiments of the present invention to provide:

New, useful, unique, efficient, nonobvious safe fibrous materials for use in spray-on insulations;

Such materials which are self-extinguishing;

Such insulations which use PVOH which is not "cooked" with an acidic medium;

Such insulations which exhibit increased toughness, water resistance, fire retardancy, bonding and wet strength;

Such insulations which can be effectively applied up to four inches in depth, and in certain aspects up to eight inches in depth; and

Methods for using such materials.

Certain embodiments of this invention are not limited to any particular individual feature disclosed here, but include combinations of them distinguished from the prior art in their structures and functions. Features of the invention have been broadly described so that the detailed descriptions that follow may be better understood, and in order that the contributions of this invention to the arts may be better appreciated. There are, of course, additional aspects of the invention described below and which may be included in the subject matter of the claims to this invention. Those skilled in the art who have the benefit of this invention, its teachings, and suggestions will appreciate that the conceptions of this disclosure may be used as a creative basis for designing other structures, methods and systems for carrying out and practicing the present invention. The claims of this invention are to be read to include any legally equivalent devices or methods which do not depart from the spirit and scope of the present invention.

The present invention recognizes and addresses the previously-mentioned problems and long-felt needs and provides a solution to those problems and a satisfactory meeting of those needs in its various possible embodiments and equivalents thereof. To one of skill in this art who has the benefits of this invention's realizations, teachings, disclosures, and suggestions, other purposes and advantages will be appreciated from the following description of preferred embodiments, given for the purpose of disclosure. The detail in these descriptions is not intended to thwart this parent's object to claim this invention no matter how others may later disguise it by variations in form or additions of further improvements.

A more particular description of embodiments of the invention briefly summarized above may be had by references to certain embodiments which are described. These embodiments are not to be used to improperly limit the scope of the invention which may have other equally effective or legally equivalent embodiments.

DESCRIPTION OF EMBODIMENTS PREFERRED AT THE TIME OF FILING FOR THIS PATENT

An acidic medium component for treating cellulose fibers, in one embodiment, is made by introducing boric acid in powder form into a hammer mill with cellulose fibers. In one aspect 17 to 22 pounds of boric acid powder is introduced into the hammer mill where it is combined with 83 to 78 pounds of fibers and milled together. In one aspect the fiber/boric acid ratio, by weight, is 41:9. The fibers in this embodiment have an average largest dimension of 2.5 mm. In one embodiment the fibers with acid are then fed to a treatment vessel wherein they are sprayed with a solution of boric acid/borax and water (e.g. an aqueous solution which is 15 to 25% by weight liquid borax/boric acid). In one embodiment about 75 pounds of fibers are treated with about 25 pounds of chemical treatment which includes 90% to 95% powdered boric acid solids by weight and 5% to 10% liquid boric acid by weight, producing about 100 pounds of treated fibers. In another aspect fibers from the hammer mill (with or without ground-in acidic solids) are immersed in a container of boric acid solution to treat them. In one aspect the total boric acid in the treated product fibers can be between 50% to 100% powdered solids and between 0% to 50% liquid boric acid (in aqueous solution); in such embodiments the acidic medium (in all forms) is between 15% to 30% by weight of the treated fibers product. In one aspect the fibers are then fed to one hose of a multi-component spray nozzle. A mixture of PVOH (in one embodiment of the invention the PVOH used is PVOH #107 commercially available from Air Products Co.) and acrylic resin (see e.g. acrylic resin as discussed in U.S. Pat. No. 4,360,440 fully incorporated herein by reference) is fed to another hose of the spray nozzle. The PVOH/acrylic resin mixture is prepared by pouring the components into a container and then mechanically mixing them, e.g. with a direct drive exterior dual helix shaft rotated at 1750 r.p.m. for five to ten minutes. In one aspect 0.23 gallons of PVOH/acrylic resin mixture is used for each pound of fibers. Pumps such as commercially available diaphragm pumps pump the adhesive mixture to the spray nozzle and the treated fibers to the spray nozzle and a spray-on insulation composition is produced.

A spray-on composition according to this invention can be effectively sprayed onto a variety of substrates such as wood, concrete, plastic, metal, ceramic, sheetrock, and paintable surfaces to any desired depth up to eight inches (in certain aspects to a desired depth up to four inches) without the undesirable falling out of flakes or chunks of material.

In one embodiment an aqueous acidic medium solution for spraying onto fibers treated in a hammer mill as described above is prepared by mixing about 700 gallons of water, about 2018 pounds of powderized boric acid, and about 2845 pounds of Borax material, e.g. Borax commercially available from U.S. Borax Co. The water is added to a glass lined vessel, and is heated by a boiler. When the temperature reaches 150 degrees F., powderized boric acid is introduced into the vessel. It takes approximately 30-45 minutes to add the boric acid. Then the borax is introduced into the vessel by conveyor belt while the vessel's contents is agitated. It takes approximately one hour to add the borax. The temperature of the total solution is raised to 180 degrees F. while agitating the solution. If the temperature in the vessel is permitted to fall below 110 degrees F., components of the solution will start to separate out, crystallize, and settle out. The resulting solution has a density of 10.20 pounds/gallon; there is about 4.64 pounds of chemical (boric acid powder plus borax) in a gallon of resulting solution; and pH of the solution is 7.33 at 110 degrees F.

In one embodiment the commercially available granular boric acid has a particle size of 100 mesh (0.01") (average largest dimension). The granular boric acid is conveyed by a screw-conveyor to a hopper from which it is fed to a pulverizer which is driven by 15 h.p. motor at R.P.M. 3600 and has sieve size of 0.035". Finished powdery boric acid with an average largest dimension of 0.035" drops into a collection hopper.

In one embodiment a known weighed amount of powder boric acid is put in a large blender and a known amount of aluminum sulfate and pigment are added. The ratio (by weight) or various ingredients is as follows:

Boric Acid 65.30%-100%

Aluminum Sulfate 0 to 24.25% (optional)

Pigment 0 to 10.45% (optional)

The chemicals and pigment are mixed by a ribbon blender to a homogenous mixture. Then the mixture is dropped into a small mixing blender;, then fed into a finishing mill by a d.c. drive chemical screw delivering an exact amount of finished dry-chemical-to-fiber in the mill which are mixed thoroughly with cellulose fibers while grinding. Treated fibers (i.e. with ground-in powderized boric acid solids, aluminum sulfate and pigment) are then drawn through a screen in the mill due to vacuum created by a downstream finishing fan. The treated fibers are then passed through a pipe. Fire retardant liquid chemical (aqueous boric acid solution prepared as described above) is fed to two nozzles in the pipe by a chemical metering pump and sprayed onto the treated fibers flowing through the pipe. The resulting mixture then goes through a fan to a cyclone which separates out undesirable fires from the fibers. The fibers are then fed to a bagger hopper and packaged into a plastic bag.

Table I presents data illustrating wet strength of a spray-on insulation product according to the present invention. Products A and C were not treated with powdered acidic solids. Product A was prepared by forming a one-inch thick piece of material with cellulose fiber (without boric acid treatment) sprayed with an adhesive, e.g. Air Products PVOH #107. About 0.23 gallons adhesive mixture were sprayed with each pound of fiber. "Reduce 5:1" means 5 parts of water were used for each part of adhesive mixture. "Set Time" is the time the sample was allowed to set prior to testing. "Tare Wt." means the weight of test apparatus connected to the test sample. "Add Wt." is the amount of additional weight hung from the sample during testing. "Total Wt." is the weight a sample supported at failure (tearing of the material). "Time To Failure" is the time taken for the sample to fail once the "Total Wt." was applied. As noted, samples A and C failed fairly quickly with relatively small weights applied to them.

Sample B was produced as described above according to the present invention by treating cellulose fiber (average largest dimension 2.5 mm; moisture content 10% to 15% by weight) with powdered boric acid solids ground-in and aqueous boric acid solution sprayed-on. Such samples supported significantly more weight (indicative of increased ability to "hang" or spray material on a substrate to a significantly increased depth).

Sample C is material as described in U.S. Pat. No. 4,360,440.

Sample D is material as described in U.S. Pat. No. 4,360,440; but which has been treated with boric acid as was Sample B.

Each Sample A-D was a sample piece 6"×8"×1".

                  TABLE I                                                          ______________________________________                                         Pro-         Set     Tare Wt.                                                                              Add Wt.                                                                               Total Wt.                                                                             Time To                              duct Reduce  Time    (grams)                                                                               (grams)                                                                               (grams)                                                                               Failure                              ______________________________________                                         A    5:1      5 Min. 80     60     140     35 Sec.                                  5:1     10 Min. 80     57     137     43 Sec.                                  5:1     30 Min. 80     81     161    100 Sec.                             ______________________________________                                         Pro-         Set                   Total Wt.                                                                             Time To                              duct Reduce  Time    Tare Wt.                                                                              Add Wt.                                                                               (grams)                                                                               Failure                              ______________________________________                                         B    5.1      5 Min. 80     220    300    230 Sec.                                  5:1     10 Min. 80     611    691    270 Sec.                                  5:1     30 Min. 80     580    660    200 Sec.                             ______________________________________                                         Pro-         Set                   Total Wt.                                                                             Time To                              duct Reduce  Time    Tare Wt.                                                                              Add Wt.                                                                               (grams)                                                                               Failure                              ______________________________________                                         C    4:1      5 Min. 82      0     <82     0 Sec.                                   4:1     10 Min. 82      0     <82     0 Sec.                              ______________________________________                                         Pro-         Set                   Total Wt.                                                                             Time To                              duct Reduce  Time    Tare Wt.                                                                              Add Wt.                                                                               (grams)                                                                               Failure                              ______________________________________                                         D    4:1      5 Min. 119    77     196     22 Sec.                                  4:1     10 Min. 119    62     181     30 Sec.                             ______________________________________                                    

Table II presents data for bond strength for a variety of adhesive mixtures according to the present invention. "SOURCE" indicates the company from which the ingredient is commercially available: "AP" is Air Products Co.; "RH" is Rohm & Haas Co.; "BFG" is B. F. Goodrich Co.; "DS" is Diamond Shamrock Co.; "TYPE" indicates the product's identifying number. "7200.5" is AP 7200 diluted half-and-half with water. "PVOH" is polyvinyl alcohol (e.g. #107 available from Air Products Co. which is not cooked with additional acid added and is not cooked with boric acid). "%A" and "%B" mean the percent by volume of each component in the resulting mixture. "MIX" indicates water-to-adhesive mixture ratio by volume. "Film Shrink None" means there was no visible loss of contact from edges of a tray holding the sample. "Film Shrink Little" means there was visible loss of such contact. "Film Shrink Some" means such visible loss of contact was readily evident. "Film Elast Excel." means there was elongation equal to about 25% or more of original length when the sample was pulled at both ends simultaneously. "Film Elast Good" means such elongation of at least 25%. "Film Strength Excel." means able to support 100 times its own weight. "Film Strength Good" means able to support 50 times its own weight. "Bond P.S.F." is bond strength in pounds per square foot of a piece of the resulting material 13"×13". "Substr." indicates a substrate to which the adhesive mixture was applied and from which the 13"×13" piece (one inch thick) was removed. "Gal" is galvalume steel. "P.M." is painted metal (steel). "Wet Strength" means strength of a fibrous mass prior to drying. Tested films were 1"×12". Materials indicated in the last two entries were prepared with the adhesives described in U.S. Pat. No. 4,360,440 without boric acid.

                                      TABLE II                                     __________________________________________________________________________     Source                                                                               Type     %  %  Mix                                                                               Film             Bond                                  "A"                                                                               "B"                                                                               "A"  "B" "A"                                                                               "B"                                                                               H2O                                                                               Color                                                                               Shrink                                                                             Elast                                                                              Strength                                                                           P.S.F.                                                                             Substr.                           __________________________________________________________________________     AP AP AP-7200                                                                             PVOH                                                                               50 50 4:1                                                                               White                                                                               None                                                                               Excel.                                                                             Excel.                                                                             215 P.M.                              AP AP AP-7200                                                                             PVOH                                                                               50 50 5:1                                                                               White                                                                               None                                                                               Excel.                                                                             Excel.                                                                             250 P.M.                              AP AP AP-7200                                                                             PVOH                                                                               50 50 6:1                 162 P.M.                              AP AP AP-7200                                                                             PVOH                                                                               50 50 7:1                 175 P.M.                              AP AP AP-7200.5                                                                           PVOH                                                                               50 50 4:1                                                                               White                                                                               Little                                                                             Good                                                                               Good                                                                                80 GAL.                              RH AP RH-1845                                                                             PVOH                                                                               50 50 4.1                                                                               Off White                                                                           Little                                                                             Good                                                                               Good                                                                                95 GAL.                              RH AP RH-1845                                                                             PVOH                                                                               50 50 8:1                  95 GAL                               BFG                                                                               AP BFG-FT9                                                                             PVOH                                                                               50 50 4:1                                                                               White                                                                               Some                                                                               Excel                                                                              Good                                                                                76 P.M.                              BFG                                                                               AP BFG-911                                                                             PVOH                                                                               50 50 4:1                                                                               Off White                                                                           Some                                                                               Good                                                                               Good                                                                               115 GAL.                                 AP      PVOH   100                                                                               5:1                                                          AP      PVOH   100                                                                               5:1                                                          AP      PVOH   100                                                                               5:1                                                       RH DS RH-6326                                                                             Silicate                                                                           60 40 4:1                                                       RH DS*                                                                               RH-6326                                                                             Silicate                                                                           60 40 4:1                 208                                      AP      PVOH   100                                                                               4:1                                                       __________________________________________________________________________

In conclusion, therefore, it is seen that the present invention and the embodiments disclosed herein and those covered by the appended claims are well adapted to carry out the objectives and obtain the ends set forth. Certain changes can be made in the subject matter without departing from the spirit and the scope of this invention. It is realized that changes are possible within the scope of this invention and it is further intended that each element or step recited in any of the following claims is to be understood as referring to all equivalent elements or steps. The following claims are intended to cover the invention as broadly as legally possible in whatever form it may be utilized. The invention claimed herein is new and novel in accordance with 35 U.S.C. § 102 and satisfies the conditions for patentability in § 102. The invention claimed herein is not obvious in accordance with 35 U.S.C. § 103 and satisfies the conditions for patentability in § 103. This specification and the claims that follow are in accordance with all of the requirements of 35 U.S.C. § 112. What is claimed is: 

We claim:
 1. A spray-on insulation composition for spraying from a spray nozzle onto a substrate to be insulated, the spray nozzle having a first hose and a second hose connected thereto, the spray-on insulation composition comprisingcellulose fibers treated with a boric acid and through the first hose of the spray nozzle for spraying onto a substrate, adhesive through the second hose of the spray nozzle, the cellulose fibers and adhesive mixed together, and the adhesive comprising polyvinyl alcohol, the polyvinyl alcohol cooked without the addition of an boric acid.
 2. The spray on insulation of claim 1 wherein the adhesive further comprises an acrylic resin.
 3. The spray-on insulation composition of claim 1 wherein the boric acid is powderized boric acid and the powderized boric acid is ground-in to the cellulose fibers with a mill.
 4. The spray-on insulation composition of claim 1 wherein the boric acid is aqueous boric acid sprayed onto the cellulose fibers.
 5. The spray-on insulation composition of claim 1 wherein the boric acid is powderized boric acid ground-in to the cellulose fibers and aqueous boric acid is sprayed onto the cellulose fibers.
 6. An adhesive composition for mixing with cellulose fibers treated with a boric acid to form a spray-on insulation, the adhesive composition comprisingpolyvinyl alcohol cooked without the addition of boric acid, and an acrylic resin.
 7. The adhesive composition of claim 6 wherein polyvinyl-alcohol, by volume, is between 5% and 95% of the adhesive composition and acrylic resin, by volume, is between 5% and 95% of the adhesive composition.
 8. The spray-on insulation of claim 1 wherein the acidic medium is between 15% to 30% by weight of the treated cellulose fibers.
 9. The spray-on insulation of claim 1 wherein the acidic medium is both ground into the cellulose fibers and sprayed thereon. 